Your physical symptoms concern me quite a bit. So does your low positive index value. You took the IgG test very soon after possible infection and your low positive could be due two several things: one, it could be a false positive as the physician suggested but if that is the case, you need a confirmatory test, preferably the Western blot. This is a CDC guidelines. Second, it could be a low positive because you have new infection and are building an antibody response. If that is the case, and future testing, your index value should be higher by quite a bit. Third, you could have a well-established herpes infection already and simply have a low positive index value as your “normal”
The best way to determine if the symptoms are due to herpes would have been to have them swab tested and look for a virus. Since that was not done, you must rely upon antibody testing. If you get another of these ulcerations, please have them swab tested right away. I would also recommend another IgG test six weeks from your most recent sexual encounter that could have put you at risk of acquiring herpes.